1. Field of the Invention
The present invention relates to an apparatus for modifying a single sheet offset duplicator to print on pre-punched and perforated continuous form paper.
2. Statement of Problem
High quality, high speed printing can be achieved through use of a standard sheet feed offset duplicator. Two basic types of duplicators are available: chute delivery and chain delivery. Chain delivery duplicators comprise the vast majority of single sheet presses. Such offset duplicators can print stacks of individual sheets at speeds of 3,000 to 10,000 impressions per hour.
In comparison to single sheet presses, machines are available to provide continuous form printing having the ability to print impressions on prepunched and perforated sheets at generally a higher cost with lower speeds. To take advantage of the continuous form (i.e., a web of paper having punched margins and perforated between sheets) printing technology, however, a print shop owner is required to invest in a separate continuous form printer while maintaining and using his current inventory of offset duplicators Many smaller print shop owners cannot afford the capital investment or the physical area required to obtain continuous form printers while maintaining their cut sheet offset duplicators.
A need, therefore, exists in the marketplace for an apparatus to simply and quickly modify the existing and numerous chute and chain delivery offset duplicators in order to convert them into continuous form printers, and be able to take advantage of the lower cost of printing while running at full machine speed without a large capital outlay. A need further exists for this kit to be able to be readily attached to and removed from the conventional offset duplicator so that the operator can selectively use either stack sheet printing or continuous form printing based upon his printing needs. Furthermore, a need exists to improve the speed of creating impressions on a conventional offset duplicator adapted for printing on continuous form paper. Finally, such a conversion apparatus must maintain the registration full speed capabilities of the machine.
It is most desirable that said conversion be of a pure mechanical nature which is more easily understood and able to be repaired if necessary by the vast majority of printers in the field. Such a pure mechanical device has a far better chance of malfunction detection and correction by the average printer/owner than one of an electronic nature/basis. Electrically/electronically controlled devices have the inherent problem of too long a lead time to obtain parts, as well as so few, relative to our whole population, technicians capable of maintaining or repairing said devices.
One approach to modifying existing offset single sheet duplicators to print on continuous form pre-punched and perforated paper is made by Sandco Inc. of 304 South Peoria, Tulsa, Oklahoma 74120-2620 as Model CFA (Continuous Forms Attachment). This attachment can be retrofitted to a number of different commercially available offset presses and requires two to four hours for the initial installation and, once initially installed, the press can be converted between printing or single sheets or printing on continuous form in about fifteen minutes.
Another approach is Model KCFF 2000 from Kinton, Inc., 2490 Kipling, Lakewood, Colo. 80215. This attachment is adaptable for use on most A. B. Dick and Ryobi duplicators, but is limited in speed to a maximum of 6000 impressions per hour. Also it has no means of clearing paper from the delivery end (exit) of the press so it subject to paper backing up except at slow speeds, especially if used on chain delivery presses. The initial installation is less than two hours and twelve to twenty minutes for changeover. The KCFF is not a pure mechanical approach and utilizes electric motors in its operation.
A search of issued patents uncovered the following:
______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ Bezler et al 4,696,229 Sept. 29, 1987 Lawrence 4,691,914 Sept. 8, 1987 Pierce 4,607,837 Aug. 26, 1986 Irvine et al 4,566,685 Jan. 28, 1986 Sanders, Jr. 4,563,102 Jan. 7, 1986 Fischer 4,423,677 Jan. 3, 1984 Fischer 4,414,896 Nov. 15, 1983 Volpe 4,326,618 Apr. 27, 1982 DuBois et al 4,300,710 Nov. 17, 1981 Kenworthy 4,175,687 Nov. 27, 1979 Hubbard 4,129,239 Dec. 12, 1978 Polko 4,066,015 Jan. 3, 1978 Hubbard 3,825,162 July 23, 1974 D'Amato 3,548,747 Dec. 22, 1970 Fisher 3,373,684 Mar. 19, 1968 Eichorn 3,209,973 Oct. 5, 1965 Hubbard et al 3,154,233 Oct. 27, 1964 Wilkins 3,049,276 Aug. 14, 1962 ______________________________________
The patent issued to Kenworthy relates to an apparatus for a continuous form printer that overcomes accumulation of errors through use of a rachet and pawl system to accurately index each sheet of the continuous forms. He accomplishes this by slightly overfeeding the continuous forms into the apparatus and then utilizing a spring motor to pull back the overfeed to just exactly the right index position when the feed drive is momentarily declutched. Kenworthy utilizes drive tractors at the output of his machine to pull the forms through the machine.
The patent to Fisher (3,373,684) pertains to a device for insuring accurate registration of the continuous form paper while being printed in standard multigraph printing machine. Fisher discloses a tractor mechanism located at the input to the machine. The drum and pressure roller of the multigraph machine pull the continuous form paper through the machine. Associated with the tractor is a mechanical locking apparatus utilizing a star wheel 35 to lockingly engage with a tooth 65. In operation, the tooth 65 locks with the star wheel 35 so that the continuous form being printed is properly registered before printing. The printing action then commences causing tooth 65 to raise thereby freeing its locked contact with the star wheel 35. The printing of the registered form commences and at the completion of the printing process, the tooth locks with the star wheel 35 to provide registration.
The patent issued to Hubbard ('233) discloses the use of front and rear feeds in a continuous form printer to provide correct registration of a continuous form with the printing mechanism. Hubbard advances the paper, a line at a time, through the printer, by using the tractors to feed the paper through the printer. The interconnections between the front and rear tractors are such to cause both tractors to operate in unison as well in order to provide sufficient longitudinal tension on the sheet material to avoid the separation of the several parts of the form at the print station and to prevent the development of air pockets between the layers of the form. Hubbard further utilizes a reluctance head and a magnetic brake to provide for precise indexing of the forms.
The patent issued to Wilkins also sets forth a high speed continuous form printer having a pair of synchronously moving tractors stationed on opposite sides of the print station. The tractors are used to drive the paper. In Wilkins, the paper tension can be adjusted by manipulating the belt linkage between the two sets of tractors.
The use of a back tractor to keep the paper properly tensioned between the front tractor and the printing mechanism is set forth by the two patents issued to Wilkins and Hubbard ('233). Both patents discuss the importance of synchronism between the front and rear tractor.
The patent to D'Amato adopts a rotary press such as a rotary intaglio press to print on continuous punched, but not perforated, web using a printing couple having a sprocket to feed the web intermittently and to release the web between successive feeding periods and a web-drawing means engaging the web on the other side of the machine for exerting a tensioning force on the web.
The patents issued to Fisher and Kenworthy generally show the concept of mechanical mechanisms providing indexing to insure exact registration for printing. Kenworthy utilizes a rachet wheel and pawl mechanical relationship to provide indexing and Fisher utilizes a star wheel and tooth. Fisher sets forth a modification to existing multigraphs and discloses the use of his tooth and star wheel mechanical relationship to index the form just prior to the printing by the drum.
Hubbard ('233) shows a combined system utilizing a reluctance indexing system combined with front and rear tractor drives. The Hubbard system provides for accurate registration and for the maintenance of desired tension while the sheet is being fed.
The remaining patents uncovered in the search are not as pertinent as the above discussed patents to the present invention.
Of all the patents, only the patent to Fisher converts a standard multigraph to print on continuous form paper. As will be found in the following, the present invention improves over the Fisher approach.
3. Solution to the Problem
The present invention offers a solution to the above problem by providing a simple mechanical conversion apparatus without the use of electric motors or control electronics for use on standard offset duplicators such as those manufactured by A. B. Dick Company of 5700 West Touhy Avenue, Chicago, Ill. 60648 and identified as Models 360, 9810 and look-a-likes. The present invention modifies the conventional offset duplicator by removing portions of the sheet delivery apparatus to the input of the duplicator for inputting the individual sheets into the offset duplicator and the chain or chute delivery located at the output of the machine. A continuous form feed apparatus is then mounted onto the offset duplicator and the modified duplicator becomes capable of printing at all speeds a duplicator can operate at such as 3000 to 10,000 impressions per hour. The novel index device incorporated into the delivery system of the present invention improves the registration of the impression on the paper over any conventional offset duplicator with a computer feeder on it especially at high speeds. It also allows registration to be adjusted while the machine is in operation. The conversion apparatus of the present invention is designed to be initially installed on an existing offset duplicator within a reasonable period of time such as ten to twenty minutes. After the initial installation, the machine can be converted between continuous form delivery and sheet delivery within five to ten minutes. The conversion apparatus of the present invention is adapted either to a chute or chain delivery feed which covers the vast majority of conventional offset duplicators in use. Being a pure mechanical device, maintenance and any repair is greatly enhanced by the average printer/owner.